The present invention relates to an automatic lathe provided with a turret device that can be fitted with a plurality of tools and select tools optionally through indexing rotations.
There has recently been an increasing demand for automatic lathes provided with a turret device that can be fitted with a plurality of tools so as to cope with a need for adopting to a large variety and small quantity manufacturing system while effecting automation as well as speedup of machining operation.
The turret device is structured such that a turret mounted on a tool rest main body is capable of executing indexing rotations so as to present any of normally 5 to 12 indexing positions optionally. Tool mounting portions are formed on a peripheral face or an outer end face of the turret, and various tools such as a turning tool, a drill, and so forth can be mounted on the respective tool mounting portions, enabling automatic selection of suitable tools according to the content of a machining operation through indexing rotations of the turret.
A pair of coupling members capable of engaging with each other and disengaging from each other (clamping/unclamping) are provided between the tool rest main body and the turret, and the turret can be rendered freely rotatable or fixedly held for positioning in a given indexing position by engaging the pair of the coupling members with each other or disengaging the same from each other.
For the coupling members described above, coupling members in the form of crown gears of a curvic coupling or the like for being meshed with each other are generally adopted.
With this type of the coupling members, engagement and disengagement thereof are normally effected by moving a coupling member disposed on the turret side in the axial direction relative to a coupling member disposed on the side of the tool rest main body. More specifically, for effecting the indexing rotation of the turret, engagement between the respective coupling members is released by moving the turret in the axial direction relative to the tool rest main body, and while the respective coupling members are kept in this state, the indexing rotation of the turret is executed.
The indexing rotation of the turret is executed subsequently to completion of a machining operation with the use of a certain tool. Accordingly, a workpiece and a main spindle table for supporting the workpiece are present in the vicinity of the turret at the time of the indexing rotation.
Hence, if the indexing rotation of the turret is executed with the turret kept in a position where it is present upon completion of the machining operation, this involves a risk of the turret and a tool fitted to the turret coming to interfere with the main spindle table and the workpiece as a result of a movement of the turret in the axial direction.
Accordingly, it has been conventionally necessary to carry out programming for a machining operation such that the indexing rotation of the turret is executed after the turret device is moved to a position where such interference can be avoided.
Such programming for a machining operation needs to be carried out by a user himself according to the content of the machining operation. A machining program to be inputted in an automatic lathe is generally developed by a user while referring to a design drawing of a product.
However, the movement of the turret in the axial direction accompanying the indexing rotation thereof can not be known from the design drawing of the product, because the movement is a motion depending on a structure of the automatic lathe. Accordingly, it has been troublesome for the user to develop a machining program always taking into account a distance of the movement. Furthermore, there has been a risk of the user""s making a mistake of developing a machining program without taking into account the movement of the turret in the axial direction associated with the indexing rotation. In case of such a mistake being made, there is a possibility of the turret and tools coming to interfere with the main spindle table and the workpiece, thereby destroying the latter.
In addition, if the turret device is caused to make an evacuating motion every time when the indexing rotation of the turret is executed, this will result in a longer machining time by at least the length of time taken for making the motion.
In the light of such circumstances as described, the present invention has been developed, and an object of the invention is to prevent the turret and a tool fitted thereto from interfering with the main spindle table and the work, and to shorten machining time by eliminating the movement of the turret relative to a lathe main body on which the main spindle table is mounted during the indexing rotations of the turret while simplifying programming by the user for a machining operation.
To this above described end, the automatic lathe according to the invention comprises the following:
(1) a lathe main body with a main spindle table mounted thereon;
(2) a tool rest main body freely movable on the lathe main body at least in a z-axis direction parallel with a main spindle axis;
(3) a turret mounted on the tool rest main body, and capable of relatively moving in the z-axis direction against the tool rest main body and indexing around a rotary center parallel to the z-axis;
(4) a pair of coupling members installed on the tool rest main body and the turret, respectively, and capable of engaging with and disengaging from each other as a result of a relative movement in the z-axis direction taking place between the tool rest main body and the turret; and
(5) control means for eliminating a relative movement between the turret and the main spindle table by moving the tool rest main body in the z-axis direction relative to the lathe main body, in synchronization with the relative movement in the z-axis direction taking place between the tool rest main body and the turret.
In this connection, the main spindle table is a constituent element for holding and rotating the workpiece. The axis of rotation for the workpiece supported by the main spindle table is called a main spindle axis, and the tool rest main body is structured so as to be freely movable at least in the z-axis direction parallel with the main spindle axis.
A plurality of tools are optionally mountable on the turret, and tools as required can be automatically selected by the indexing rotation of the turret. And through a relative movement between the main spindle table and the tool rest main body, the workpiece supported by the main spindle table is machined into a required shape.
The turret is clamped to the tool rest main body by the pair of the coupling members. During the indexing rotation for selecting a tool, the pair of coupling members are unclamped by relatively moving the tool rest main body against the turret in the z-axis direction, so that the turret is rendered freely indexable.
Hereupon, the control means causes the tool rest main body to move in the z-axis direction relative to the lathe main body, in synchronization with the relative movement in the z-axis direction taking place between the tool rest main body and the turret. The movement of the tool rest main body is adjusted in respect of direction and moving distance such that the relative movement between the turret and the main spindle table is eliminated.
As a result of such control of movement as described, there will occur no relative displacement of the turret and a tool fitted thereto against the main spindle and a work, thereby eliminating a risk of mutual interference taking place among these constituent elements including the work.
At the time of the indexing rotation of the turret, the relative displacement between the workpiece supported by the main spindle table and the tool fitted to the turret is thus eliminated, so programming for machining may be carried out by a user on the basis of a position of the workpiece relative to the tool at the time of completion of a machining operation. Accordingly, there will be no need to take into account the relative displacement between the workpiece and the turret, accompanying the indexing rotation of the turret, as with the conventional case, thereby facilitating operation.
Further, since there will be no need of evacuating the turret device prior to the indexing rotation of the turret, machining time can be shortened by at least a length of time saved due to omission of such a motion.
Also, if a main spindle table is movable on a lathe main body at least in a z-axis direction parallel with a main spindle axis, the invention may have such a configuration that control means is able to eliminate a relative movement between a turret and the main spindle table by moving the main spindle table in the z-axis direction relative to the lathe main body, in synchronization with a movement of the turret in the z-axis direction.
The movement of the main spindle table in this case is adjusted in respect of direction and moving distance in such a way as to eliminate the relative movement between the turret and the main spindle table.
The present invention may also be applicable to an automatic lathe comprising a tool rest main body that is freely movable on a lathe main body at least in an x-axis direction orthogonal to a main spindle axis, and a pair of coupling members capable of engaging with and disengaging from each other as a result of a relative movement in the x-axis direction taking place between the tool rest main body and a turret.
In this case, the invention comprises control means for eliminating a relative movement between the turret and a main spindle table by moving the tool rest main body in the x-axis direction relative to the lathe main body, in synchronization with the relative movement in the x-axis direction taking place between the tool rest main body and the turret.
The movement of the tool rest main body in this case is adjusted in respect of direction and moving distance in such a way as to eliminate the relative movement between the turret and the main spindle table.
Further, the present invention can be embodied by a method of controlling an automatic lathe comprising a lathe main body with a main spindle table mounted thereon, a tool rest main body freely movable on the lathe main body at least in a z-axis direction parallel with a main spindle axis, a turret mounted on the tool rest main body and capable of relatively moving in the z-axis direction against the tool rest main body and indexing around a rotary center parallel to the z-axis, and a pair of coupling members installed on the tool rest main body and the turret, respectively, and capable of engaging with and disengaging from each other as a result of a relative movement in the z-axis direction taking place between the tool rest main body and the turret.
That is, with the method of controlling the automation lathe according to the invention, a relative movement between the turret and the main spindle table is eliminated by moving the tool rest main body in the z-axis direction relative to the lathe main body, in synchronization with the relative movement in the z-axis direction taking place between the tool rest main body and the turret.
The movement of the tool rest main body in this case is adjusted in respect of direction and moving distance in such a way as to eliminate the relative movement between the turret and the main spindle table.
Similarly, the present invention can also be embodied by a method of controlling an automatic lathe comprising a lathe main body with a tool rest main body mounted thereon, a main spindle table movable on the lathe main body at least in a z-axis direction parallel with a main spindle axis, a turret mounted on the tool rest main body so that the turret can freely move in the z-axis direction and freely index around a rotary center parallel to the z-axis, and a pair of coupling members installed on the tool rest main body and the turret, respectively, and capable of engaging with and disengaging from each other as a result of a movement of the turret in the z-axis direction.
That is, with this method, control is effected such that a relative movement between the turret and the main spindle table is eliminated by moving the main spindle table in the z-axis direction relative to the lathe main body, in synchronization with the movement of the turret in the z-axis direction.
The movement of the main spindle table in this case as well is adjusted in respect of direction and moving distance in such a way as to eliminate the relative movement between the turret and the main spindle table.
Furthermore, the present invention can also be embodied by a method of controlling an automatic lathe comprising a lathe main body with a main spindle table mounted thereon, a tool rest main body freely movable on the lathe main body at least in a x-axis direction orthogonal to a main spindle axis, a turret mounted on the tool rest main body and capable of relatively moving in the x-axis direction against the tool rest main body and indexing around a predetermined rotary center, and a pair of coupling members installed on the tool rest main body and the turret, respectively, and capable of engaging with and disengaging from each other as a result of a relative movement in the x-axis direction taking place between the tool rest main body and the turret.
That is, with this method, control is effected such that a relative movement between the turret and the main spindle table is eliminated by moving the tool rest main body in the x-axis direction relative to the lathe main body, in synchronization with the relative movement in the x-axis direction taking place between the tool rest main body and the turret.
The movement of the main spindle table in this case as well is adjusted in respect of direction and moving distance in such a way as to eliminate the relative movement between the turret and the main spindle table.
With respective configurations described in the foregoing, there will occur no relative displacement of the turret and a tool fitted thereto, against the main spindle table and a work, so that a risk of mutual interference occurring among those constituent elements including the work is eliminated.
In addition, since at the time of the indexing rotation of the turret, the relative displacement between the workpiece supported by the main spindle table and the tool fitted to the turret is eliminated, programming for machining may be carried out by a user on the basis of a position of the workpiece relative to the tool upon completion of a machining operation. Accordingly, there will be no need of taking into account the relative displacement between the workpiece and the turret, accompanying the indexing rotation of the turret, as with the conventional case, thereby facilitating operation.
Furthermore, since there will be no need of evacuating the turret device prior to the indexing rotation of the turret, machining time can be shortened by at least a length of time saved due to omission of such a motion.